A liquid crystal display, or LCD, is a display apparatus that utilizes an image display panel formed of a pair of transparent sheets of polarizing material separated by a liquid containing rod-shaped crystals. The polarizing axes of these two transparent sheets are aligned perpendicular to each other. The LCD is constructed to display an image by passing an electric current through the liquid that causes the crystals to align to block light. Each crystal can be controlled individually and essentially acts like a shutter. Current is applied to specific pixel-like areas, and those crystals align to create dark or light images. The dark areas are combined with the light areas to create text and images on the panel. The LCD panel itself does not generate light and thus requires a light source. Accordingly, the panels are back-lit or increasingly side-lit which enables very thin form factors.
One measure of the quality of a television picture is the Mura, which is a Japanese origin term for unevenness or inconsistency. In the context of televisions, and LCD televisions in particular, dark screen mura refers to the non-uniformity of the darkness of the screen. In other words, when the LCD panel receives an input directing it to prevent transmission of any light, the blackness of the screen may in fact vary, with relatively lighter or darker areas. This variability is undesirable if it is pronounced enough to be recognizable to the human eye.